m the Duke of Charmerace." And he opened
the door.

"It was M. Formery's orders, your Grace," stammered the policeman
doubtfully.

"M. Formery's orders?" said the Duke, standing on the top step. "Call
me a taxi-cab, please."

The concierge, who stood beside the policeman, ran down the steps and
blew his whistle. The policeman gazed uneasily at the Duke, shifting
his weight from one foot to the other; but he said no more.

A taxi-cab came up to the door, the Duke went down the steps, stepped
into it, and drove away.

Three-quarters of an hour later he came back, having changed into
clothes more suited to a Paris drawing-room. He went up to the
drawing-room, and there he found Guerchard, M. Formery, and the
inspector, who had just completed their tour of inspection of the house
next door and had satisfied themselves that the stolen treasures were
not in it. The inspector and his men had searched it thoroughly just to
make sure; but, as Guerchard had foretold, the burglars had not taken
the chance of the failure of the police to discover the opening between
the two houses. M. Formery told the Duke about their tour of inspection
at length. Guerchard went to the telephone and told the exchange to put
him through to Charmerace. He was informed that the trunk line was very
busy and that he might have to wait half an hour.

The Duke inquired if any trace of the burglars, after they had left
with their booty, had yet been found. M. Formery told him that, so far,
the detectives had failed to find a single trace. Guerchard said that
he had three men at work on the search, and that he was hopeful of
getting some news before long.

"The layman is impatient in these matters," said M. Formery, with an
indulgent smile. "But we have learnt to be patient, after long
experience."

He proceeded to discuss with Guerchard the new theories with which the
discovery of the afternoon had filled his mind. None of them struck the
Duke as being of great value, and he listened to them with a somewhat
absent-minded air. The coming examination of Sonia weighed heavily on
his spirit. Guerchard answered only in monosyllables to the questions
and suggestions thrown out by M. Formery. It seemed to the Duke that he
paid very little attention to him, that his mind was still working hard
on the solution of the mystery, seeking the missing facts which would
bring him to the bottom of it. In the middle of one of M. Formery's
more elaborate dissertat